Vacuum device

ABSTRACT

A vacuum device is provided which forms an autarkic subassembly and includes a vacuum container, a vacuum pump connected to the vacuum container, a vacuum connection for connecting to an external installation, and a control device designed for control of the vacuum pump. The vacuum device serves as a suction device to produce a vacuum in and to suck or draw off gas from this connected installation. The vacuum device is designed as an autarkic (self-sufficient or self-contained) subassembly, which can be connected for example to an electron microscope.

BACKGROUND OF THE INVENTION

The invention relates to a vacuum device for producing a vacuum, in particular for use with an electron microscope.

With electron microscopes, the sample chamber is evacuated for the examination. As a rule, a turbo-pump is provided for the evacuation, which is an integral part of the electron microscope and is integrated into it. However, turbo-pumps are mostly not capable of pumping away directly into the atmosphere. For this reason, it is known to arrange a fore-pump downstream of the turbo-pump and this fore-pump leads away the residual gas quantities. These fore-pumps are connected externally to the electron microscope. It is annoying that the additional fore-pumps produce additional noise and have an additional energy requirement during operation.

BRIEF SUMMARY OF THE INVENTION

With regard to these problems, it is an object of the invention to provide a vacuum device which permits the pumping procedure to takes its course with a minimized energy requirement and minimized noise level, in particular for use with an electron microscope.

This object is achieved by a vacuum device which forms an autarkic subassembly and comprises a vacuum container, a vacuum pump connected to the vacuum container, a vacuum connection for connecting to an external installation, and a control device designed for control of the vacuum pump. Preferred embodiments are described in the following description and the attached drawings.

The vacuum device according to the invention serves as a suction device, in order to produce a vacuum in a connected installation and to suck or draw off gas from this connected installation. The connection to the external component or to an external installation is effected via a vacuum connection which is provided on the vacuum device. The vacuum device according to the invention is designed as an autarkic (self-sufficient or self-contained) subassembly, which can be connected via the vacuum connection to an external installation, for example to an electron microscope, from which gas is to be drawn off or extracted. The design as an autarkic subassembly has the advantage that the installation can be provided independently of the electron microscope and connected to the microscope in a simple manner, in order to replace conventional fore-pumps. An intervention in the control of the electron microscope is not necessary, since the autarkic subassembly contains all components, optionally valves and sensors, which are suitable for producing the vacuum at the vacuum connection, and a suitable control device.

The vacuum device on the one hand comprises a vacuum pump and on the other hand a vacuum container, for producing the vacuum. The vacuum pump is connected to the vacuum container, in order to be able to evacuate the vacuum container and to be able to produce a vacuum relative to the surrounding pressure in the vacuum container. The vacuum connection for connection to an external installation is connected to the vacuum container, so that a necessary suction or vacuum can be provided at the vacuum connection, by the vacuum in the vacuum container. This, even without continuous operation of the vacuum pump, permits the provision of the desired vacuum at the vacuum connection.

Therefore, the vacuum pump does not need to run in a continuous manner, but rather the vacuum pump can be set into operation always for comparatively short operating times, in order to produce a vacuum in the vacuum container. The evacuated vacuum container thus provides the necessary suction at the vacuum connection at times in which the vacuum pump does not run. Only if the vacuum in the vacuum container falls below a certain limit, i.e. the pressure in the container rises above a defined pressure value, is the vacuum pump then set into operation again. On the one hand the energy consumption and on the other hand the noise level are reduced due to the fact that the vacuum pump does not need to run continuously, since the installation can then be operated almost completely without noise, even when the vacuum pump is switched off.

For control the vacuum device, as an integral part of the autarkic subassembly, comprises a control device which is designed for the control of the vacuum pump. In particular, the control device is designed such that it switches the vacuum pump on and off, so that a desired vacuum level in the vacuum container can be constantly maintained. For this, a pressure sensor monitoring the pressure on the inside can be provided inside the vacuum container or be connected to the interior of the vacuum container. The pressure sensor can be designed, for example, in the form of measurement tube applied onto the vacuum container. The pressure sensor is connected to the control device in a suitable manner, and the control device is designed such that it switches the vacuum pump on and off depending on sensor signals detected by the pressure sensor, in order to maintain the desired vacuum level inside the vacuum container.

Preferably, the vacuum device comprises at least one valve, and the control device is designed for the control of this at least one valve. With regard to this valve, it can a shut-off valve, for example, which is opened and closed by actuation of the control device. In particular, it can be a shut-off valve which closes and opens the vacuum container, in particular in a flow path which leads from the vacuum container to the vacuum connection. Alternatively or additionally, a corresponding valve can be arranged in a flow path between the vacuum chamber and the vacuum pump. Moreover, a valve for venting the vacuum pump can be provided when the vacuum pump is not running.

As stated, the vacuum device is particularly preferably designed for use with an electron microscope. For this, the vacuum device is designed as an autarkic subassembly, which can be connected onto an electron microscope, in order to replace there a conventional pump for leading away residual gas quantities. The vacuum device is thereby controlled by its own controller, which is to say control device.

For this purpose, the vacuum device is further preferably designed such that it is connectable with its vacuum connection to an electron microscope in a manner that the vacuum device is connected downstream of a turbo-pump of the electron microscope. Thus, the vacuum device then leads away the residual gas quantities which are led out by the turbo-pump.

According to a further embodiment, at least one first shut-off valve, which is actuatable by the control device, i.e., which can be opened and closed by the control device, is arranged in a flow path between the vacuum container and the vacuum pump. Thus, the flow path can be closed after producing the vacuum in the vacuum container.

The vacuum connection is preferably connected to the flow path between the first shut-off valve and the vacuum pump. The vacuum connection can thereby be arranged directly on the flow path or be connected to the flow path by a conduit branching from the flow path. With this arrangement, the first shut-off valve serves for connecting or disconnecting the inside of the vacuum container to the vacuum connection, depending on whether the shut-off valve is opened or closed. Thus, the suction function which is produced by the vacuum container, can be switched on and off by actuating the shut-off valve.

A second shut-off valve, which is actuatable by the control device, is arranged in the flow path between the vacuum container and the vacuum pump, preferably between the vacuum connection and the vacuum pump. Thus, the vacuum connection is preferably situated in a section of the flow path between the first and the second shut-off valve, i.e., which branches from this section. By actuation of the shut-off valves, it is possible to selectively bring the vacuum connection in flow connection with the vacuum pump or with the vacuum container. The vacuum connection can also be simultaneously connected to the vacuum container and the vacuum pump by simultaneously opening both shut-off valves. Alternatively, only the second shut-off valve can be provided between the vacuum connection and the vacuum pump, and the first shut-off valve between the vacuum connection and the vacuum container can be dispensed with. With this arrangement, the vacuum connection would then also be connected to the vacuum container. The actuation of the shut-off valves is effected by the control device. This is designed such that it actuates the shut-off valves, preferably depending on sensor signals, in particular on the signal of a pressure sensor on or in the vacuum container. Thus, for the case where the vacuum in the vacuum container is not sufficient, the vacuum pump can be set into operation, and by opening the shut-off valves can be brought into connection with the vacuum container and, optionally, additionally with the vacuum connection, in order to maintain the desired vacuum there.

It is to be understood that another arrangement of the vacuum container, the vacuum connection and vacuum pump with possibly required valves is also possible, wherein the arrangement should preferably be designed such that the vacuum pump on the one hand can produce the vacuum in the vacuum container, but on the other hand can also make a vacuum directly available at the vacuum connection. Moreover, the vacuum container should be able to be brought into connection with the vacuum connection. Suitable shut-off valves which are actuatable by the control device are provided, in order to switch the individual flow paths.

Further preferably, the vacuum device comprises at least one vent opening which can be closed by a valve. This valve too is preferably controllable by the control, so that the control device can open and close this valve. The vent opening can be opened, in order to ventilate the installation when it is taken out of operation.

With regard to the control device, it is preferably a memory-programmable control, so that desired operating programs can be set and stored in the device in a simple manner.

According to a further embodiment, the control device comprises at least one signal input, via which a switch signal can be given to the control device, wherein the control device is designed in a manner such that on receiving the switch signal, it activates the vacuum pump or at least one valve, in a manner such that a vacuum is made available at the vacuum connection. The signal input can be connected to a signal output of an electron microscope, for example, so the control of the electron microscope signals to the control device of the autarkic vacuum device that a sucking by the vacuum device is necessary for evacuating the sample chamber of the electron microscope.

Preferably, the signal input can be subjected to mains voltage as a switch signal. This permits the vacuum device according to the invention to be connected very simply to the electron microscope instead of to a common fore-pump. Electron microscopes as a rule have a mains voltage connection for connection to such a fore-pump, wherein the mains voltage connection is switched on and off by the control of the electron microscope, in order to switch the pump on and off. This switched mains voltage can thus be used as a switch signal for the autarkic vacuum device.

According to a further embodiment of the invention, the control device can be designed in a manner such that operating times for the vacuum pump can be preset. Thus, the vacuum device can be operated such that the vacuum pump is operated at preferably previously set dates or times, for example at times in which one does not operate a connected electron microscope, so that the work with the electron microscope is preferably not disturbed by the operation of the vacuum pump. Moreover, the operating times can be selected such that, for example, the vacuum device is taken out of operation or is operated with a reduced vacuum at the weekend, in order to save energy.

The control device is further preferably designed in a manner such that it maintains the vacuum in the inside of the vacuum container below a defined limit value, by switching the vacuum pump on and off, wherein different limit values can be prescribed in a time-dependent manner. Thus, for example the vacuum can be reduced at times at which one works less, for example at the weekend, in order to save energy. For this then, a larger vacuum, i.e. a lower absolute vacuum pressure, can be made available at the main working times, in order to ensure a greater sucking performance without operation of the vacuum pump.

Further preferably, the control device is designed in a manner such that it controls the vacuum pump and at least one valve, in a manner such that the vacuum container and the vacuum pump can selectively and/or simultaneously be brought into suction connection with the vacuum connection. Thus, the vacuum at the vacuum connection, optionally, can be produced alone by the vacuum pump, for example if a too high pressure prevails in the vacuum container, in order to provide the desired suction performance. Accordingly, preferably the vacuum container can also alone provide the desired suction performance, in order to permit the vacuum device to operate in a manner in which noise is particularly minimized. Moreover, for example when starting up or pumping up, a vacuum may be made available via the vacuum container, in order to minimize the power uptake when starting the pumping. Thus, it is indeed precisely when a high sucking power is desired that the vacuum container and the vacuum pump can be simultaneously connected to the vacuum connection.

According to a further embodiment, the control device comprises at least one sensor connection and is designed in a manner such that a control of the vacuum pump and/or the at least one valve is effected in dependence on a sensor signal present at the sensor connection. Thus, at least one external parameter can be detected via the sensor connection, and the vacuum device is operated in dependence on this parameter, for example a temperature. For this purpose, the sensor connection can be connected or connectable to a temperature sensor, for example in order to detect the temperature of the turbo-pump of the electron microscope and to control the vacuum device in dependence on this temperature. Thus, the control device can set the limit values for the vacuum in the vacuum container in dependence on the temperature of the turbo-pump, in order to prevent certain temperature limit values at the turbo-pump being exceeded.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:

FIG. 1 is a schematic diagram of a vacuum device according to a first embodiment of the invention; and

FIG. 2 is a schematic diagram of a vacuum device according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a vacuum device 2 according to an embodiment of the invention, in combination with an electron microscope 4. The electron microscope 4, in a known manner, comprises a turbo-pump as well as a control device for the control of the turbo-pump inside microscope. The electron microscope 4 comprises a suction connection 6, via which the residual gas can be conveyed away, in a known manner, via an external fore-pump connected downstream of the turbo-pump.

According to the invention, now instead of such a fore-pump, the vacuum device 2 according to the invention is connected to the electron microscope 4. The vacuum device 2, as a central integral part or constituent, comprises a vacuum container 8 as well as a pump or vacuum pump 10. The vacuum pump 10 is connected to the vacuum container 8 via a conduit 12, which creates a flow path from the vacuum container 8 to the vacuum pump 10, so that the vacuum pump 10 is capable of evacuating the vacuum container 8.

A first shut-off valve 14 and a second shut-off valve 16 are arranged in the conduit 12. Moreover, a vacuum connection 18, which here is connected to the suction connection 6 of the electron microscope 4, branches from the conduit 12 between the first shut-off valve 14 and the second shut-off valve 16. Moreover, a vent valve 20 is arranged on the end of the conduit 12 away from the vacuum container 8. The three valves, i.e. the first shut-off valve 14, the second shut-off valve 16 and the vent valve 20, are designed as electrically switchable valves.

A control device 22 in the form of a memory-programmable control (MPC) is present for the control of these valves ,as well as of the vacuum pump 10. A pressure sensor 24, whose output signal is led to the control device 22, is arranged on the vacuum container 8. The described valves, the vacuum pump 10, the vacuum container 8 and the control device 22 form an autarkic vacuum device 2, which as an autarkic subassembly is connectable to an electron microscope 4. In particular, the control device is thereby designed in an autarkic manner, so that the vacuum device 2 can be controlled independently of the electron microscope 4.

In the example shown here in FIG. 1, the control device 22, apart from a mains connection 26 for electricity supply, comprises a signal input 28. An electrical lead 30, which is connected to a switchable output of the electron microscope 4, is connected to the signal input 28. This switchable output usually serves for the connection of an external pump to the electron microscope 4 and has the mains voltage. This mains voltage, which is usually used for the operation of the pump, is used here as a pure switch signal, which is led to the signal input 28 of the control device 22. Thus, no further wiring or linking to the control of the electron microscope 4 is necessary.

The control of the electron microscope 4 subjects the output, to which an external pump is usually connected, to a voltage when a gas suctioning from the outside is necessary. This signal via the electrical lead 30 is detected by the control device 22 of the vacuum device 2 and can accordingly open the first shut-off valve 14, in order to subject the vacuum connection 18 to a vacuum from the vacuum container 8 and thus to produce a suction or vacuum in the vacuum connection 18. Alternatively, the control device 22 could open the second shut-off valve 16 and set the vacuum pump 10 in operation, in order to produce a vacuum at the vacuum connection 18. Also, both shut-off valves 14 and 16 can be opened by the control device 22, for a high sucking performance.

However, it is preferable for the suction performance or power at the vacuum connection 18 to be provided by the vacuum container 8. The control device 22 via the pressure sensor 24 monitors the vacuum in the vacuum container 8 and, when the vacuum in the vacuum container 8 becomes too low, i.e. when the absolute pressure exceeds a defined nominal value, switches the vacuum pump 10 on and opens both shut-off valves 14 and 16, so that the vacuum pump 10 evacuates the vacuum container 8. For the control of the valves 14, 16 and 20 as well as of the vacuum pump 10, these are connected to the control device 2 via electrical leads 32. The vent valve 20 is opened by the control device 22 when the complete installation is to be vented.

The control device 22 is designed such that the running time of the vacuum pump 10 is preferably minimized, in order to save energy and to keep the noise level of the vacuum device 2 as low as possible. Moreover, it can be designed such that it permits a time-dependent control so that, for example, a maximal vacuum in the vacuum container 8 is produced by operation of the vacuum pump 10, for example at the beginning of the work in a laboratory, and the vacuum pump 10 can then be switched off for an duration as long as possible, so that no noises or vibrations of the vacuum pump interfere, and the necessary suction power is provided by the vacuum container 8 alone.

Moreover, it is possible by suitable programming of the control device 22 to adapt the vacuum level in the vacuum container 8 to different times of the day or times of the week. For example, the vacuum level can be reduced at the weekend, i.e. to only a low vacuum in which a higher absolute pressure is made available in the vacuum container, in order thus to reduce the operating times of the vacuum pump 10 and thus the energy consumption.

It is conceivable to provide the control device 22 with further signal inputs, for example in order to further permit a temperature-dependent control, for example in a manner dependent on the temperature of a turbo-pump in the electron microscope 4.

The arrangement of the valves and components can also be effected in a different manner, thus optionally one can make do without the first shut-off valve 14, for example. This arrangement, however, then has the disadvantage that when the electron microscope 4 is vented, the vacuum container 8 is also always vented as well. This inherent venting of the vacuum container 8 is prevented by the first shut-off valve 14.

An alternative arrangement is moreover shown in FIG. 2. This arrangement differs from the arrangement in FIG. 1 in that the second shut-off valve 16 is not connected to the flow path from the first shut-off valve 14 to the vacuum connection 18, but directly to the vacuum container 8. The advantage of this arrangement is that the vacuum container 8 can be simultaneously evacuated also during the venting of the electron microscope 4. The fact that the pumping-away effect is greater than with a slowly starting pump, so that undesired swirling in the electron microscope 4 can occur, is a possible disadvantage with this arrangement.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims. 

I/We claim:
 1. A vacuum device comprising: a vacuum container, a vacuum pump connected to the vacuum container, a vacuum connection for connecting the vacuum device to an external installation, and a control device designed to control the vacuum pump, wherein the vacuum device forms an autarkic subassembly to the external installation.
 2. The vacuum device according to claim 1, further comprising at least one valve, and wherein the control device is designed to control the at least one valve.
 3. The vacuum device according to claim 1, wherein the external installation is an electron microscope.
 4. The vacuum device according to claim 3, wherein the vacuum connection is connectable to the electron microscope such that the vacuum device is arranged downstream of a turbo-pump of the electron microscope.
 5. The vacuum device according to claim 1, further comprising at least a first shut-off valve actuatable by the control device and arranged in a flow path between the vacuum container and the vacuum pump.
 6. The vacuum device according to claim 5, wherein the vacuum connection is arranged on the flow path.
 7. The vacuum device according to claim 5, further comprising a second shut-off valve actuatable by the control device and arranged in the flow path, between the vacuum connection and the vacuum pump.
 8. The vacuum device according to claim 1, further comprising a vent opening closable by a valve.
 9. The vacuum device according to claim 8, wherein the control device is designed to control the valve of the vent opening.
 10. The vacuum device according to claim 1, wherein the control device is a memory-programmable control.
 11. The vacuum device according to claim 1, wherein the control device comprises at least one signal input by which a switch signal may be led to the control device, wherein the control device is designed such that on receipt of the switch signal the control device activates the vacuum pump and/or at least one valve to provide a vacuum at the vacuum connection.
 12. The vacuum device according to claim 11, wherein the signal input is subjected to mains voltage as a switch signal.
 13. The vacuum device according to claim 1, wherein the control device is designed such that operating times for the vacuum pump are preset.
 14. The vacuum device according to claim 1, wherein the control device is designed such that by switching the vacuum pump on and off, the vacuum pump maintains the pressure inside the vacuum container below a predefined limit value, and different limit values can be set in a time-dependent manner.
 15. The vacuum device according to claim 1, wherein the control device is designed such that it controls the vacuum pump and at least one valve, such that the vacuum container and the vacuum pump can be selectively and/or simultaneously brought into suction connection with the vacuum connection.
 16. The vacuum device according to claim 1, wherein the control device comprises at least one sensor connection and is designed such that control of the vacuum pump and/or of at least one valve is effected in dependence on a sensor signal present at the sensor connection
 17. The vacuum device according to claim 16, wherein the sensor connection is connected or is connectable to a temperature sensor. 